RDF System Management Manual
Table Of Contents
- RDF System Management Manual
- What’s New in This Manual
- About This Manual
- 1 Introducing RDF
- RDF Subsystem Overview
- RDF Processes
- RDF Operations
- Reciprocal and Chain Replication
- Available Types of Replication to Multiple Backup Systems
- Triple Contingency
- Loopback Configuration (Single System)
- Online Product Initialization
- Online Database Synchronization
- Online Dumps
- Subvolume- and File-Level Replication
- Shared Access DDL Operations
- EMS Support
- SMF Support
- RTD Warning Thresholds
- Process-Lockstep Operation
- Support for Network Transactions
- RDF and NonStop SQL/MX
- Zero Lost Transactions (ZLT)
- Monitoring RDF Entities With ASAP
- 2 Preparing the RDF Environment
- 3 Installing and Configuring RDF
- 4 Operating and Monitoring RDF
- 5 Managing RDF
- Recovering From File System Errors
- Handling Disk Space Problems
- Responding to Operational Failures
- Stopping RDF
- Restarting RDF
- Carrying Out a Planned Switchover
- Takeover Operations
- Reading the Backup Database
- Access to Backup Databases in a Consistent State
- RDF and NonStop SQL/MP DDL Operations
- RDF and NonStop SQL/MX Operations
- Backing Up Image Trail Files
- Making Online Dumps With Updaters Running
- Doing FUP RELOAD Operations With Updaters Running
- Exception File Optimization
- Switching Disks on Updater UPDATEVOLUMES
- 6 Maintaining the Databases
- 7 Online Database Synchronization
- 8 Entering RDFCOM Commands
- 9 Entering RDFSCAN Commands
- 10 Triple Contingency
- 11 Subvolume- and File-Level Replication
- 12 Auxiliary Audit Trails
- 13 Network Transactions
- Configuration Changes
- RDF Network Control Files
- Normal RDF Processing Within a Network Environment
- RDF Takeovers Within a Network Environment
- Takeover Phase 1 – Local Undo
- Takeover Phase 2 – File Undo
- Takeover Phase 3 – Network Undo
- Takeover Phase 3 Performance
- Communication Failures During Phase 3 Takeover Processing
- Takeover Delays and Purger Restarts
- Takeover Restartability
- Takeover and File Recovery
- The Effects of Undoing Network Transactions
- Takeover and the RETAINCOUNT Value
- Network Configurations and Shared Access NonStop SQL/MP DDL Operations
- Network Validation and Considerations
- RDF Re-Initialization in a Network Environment
- RDF Networks and ABORT or STOP RDF Operations
- RDF Networks and Stop-Update-to-Time Operations
- Sample Configurations
- RDFCOM STATUS Display
- 14 Process-Lockstep Operation
- Starting a Lockstep Operation
- The DoLockstep Procedure
- The Lockstep Transaction
- RDF Lockstep File
- Multiple Concurrent Lockstep Operations
- The Lockstep Gateway Process
- Disabling Lockstep
- Reenabling Lockstep
- Lockstep Performance Ramifications
- Lockstep and Auxiliary Audit Trails
- Lockstep and Network Transactions
- Lockstep Operation Event Messages
- 15 NonStop SQL/MX and RDF
- Including and Excluding SQL/MX Objects
- Obtaining ANSI Object Names From Updater Event Messages
- Creating NonStop SQL/MX Primary and Backup Databases from Scratch
- Creating a NonStop SQL/MX Backup Database From an Existing Primary Database
- Online Database Synchronization With NonStop SQL/MX Objects
- Offline Synchronization for a Single Partition
- Online Synchronization for a Single Partition
- Correcting Incorrect NonStop SQL/MX Name Mapping
- Consideration for Creating Backup Tables
- Restoring to a Specific Location
- Comparing NonStop SQL/MX Tables
- 16 Zero Lost Transactions (ZLT)
- A RDF Command Summary
- B Additional Reference Information
- C Messages
- D Operational Limits
- E Using ASAP
- Index
Zero Lost Transactions (ZLT)
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Phase 2 (Takeover Processing)
Phase 2 (Takeover Processing)
The initial part of Phase 2 takeover processing is performed by the purger in building
the undo lists. When an updater reaches the end-of-file of its image trail, it asks the
purger for an undo list. (The purger cannot start building the undo lists until all
receivers have finished their ZLT processing.) The updaters use those lists to back out
any audit for transactions that were unresolved on the primary system at the time of
the unplanned outage.
ZLT Events
Event Management System (EMS) events are logged to report the progress of the ZLT
operation in the various RDF processes. For descriptions of these messages, see
messages 900 through 903 in appendix C.
Error Conditions
If the standby system is different from the backup system and the monitor cannot reach
the standby system to start the extractor(s), the takeover operation aborts. If that
happens, you must bring the standby system up (and make sure it is available to the
backup system by way of the Expand network) and then reissue the TAKEOVER
command.
If an extractor cannot find an audit file it needs because the disk has not yet been
mounted, the extractor abends and the takeover operation aborts. If you have not yet
mounted the disk the extractor needs, you must mount it before reissuing the
TAKEOVER command. If the remote mirror cannot be mounted and you want to do
the takeover without the ZLT guarantee, you can alter the RDF REMOTE MIRROR
attribute on the backup system to off. When you reissue the TAKEOVER command,
the takeover then proceeds as a normal takeover operation (without ZLT).
STATUS RDF
You cannot issue the STATUS RDF command from the standby system; it must only be
issued from the backup system.
If a takeover does not involve ZLT, the extractor is not included in the STATUS display
during an RDF takeover operation. With ZLT configured and enabled, the STATUS
RDF display changes during an RDF takeover. During phase 1 (ZLT processing),
status is displayed for the extractor(s), consisting of process name, sno, rba, cpus,
error. The RTD field, however, is left blank.
RDFCOM INFO and SHOW Commands
The INFO command output includes the RDF and extractor configuration attributes for
ZLT, as does the output for the SHOW command.